The trip, his first to the country as president, is part of his sweep across the Middle East, which will include visits to the West Bank and Jordan.

Obama's first stop Wednesday will be a visit to an Iron Dome missile defense launcher in Tel Aviv.

Designed by Israel and funded by the United States, the battery was deployed at the height of November's fighting between Israel and Hamas. It intercepted a rocket headed for Tel Aviv, Israeli ambassador to the United States Michael Oren said.

Afterward, Obama will head to Jerusalem to meet Israeli President Shimon Peres and Prime Minister Benjamin Netanyahu, where Iran is expected to be a hot topic.

Concerns about Iran

On Tuesday, Peres conceded his country may disagree at times with the White House over Iran's nuclear progress. But he said he is "free of doubts" that Obama would use military force if necessary to stop Tehran from developing a nuclear bomb.

As he prepared for this trip, Obama told an Israeli TV station he believed there was still a year or so before Iran reached the final development stage -- suggesting he believes there is more time for diplomacy than the Israeli prime minister would like.

But Peres played down disagreements between the U.S. and Israeli intelligence assessments of Iran's progress toward a bomb.

"There may be some differences in timing, but basically we support the policy of the president of the United States," Peres said.

Netanyahu has voiced concerns that Washington has a less urgent view of Iran's progress toward developing a nuclear warhead, but has welcomed the administration's more muscular language recently that "all options" are on the table.

A shaky relationship

Obama's relationship with Netanyahu has never been warm, and the Israeli prime minister supported Republican challenger Mitt Romney in last year's presidential election.

Despite getting off to a rocky start with Netanyahu by pushing for a freeze of Israeli settlements, Obama's vocal support for him through the November crisis with Hamas and U.S. financial support for the Iron Dome anti-missile program could pave the road for greater trust in the relationship.

The Israeli-Palestinian dispute

White House officials say Obama is not carrying a new peace initiative and is hardly optimistic there is solid ground to try to revive negotiations.

Most of all, the president's aides say, he wants to assess how prepared -- if at all -- Netanyahu and Palestinian leader Mahmoud Abbas are to return to negotiations.

Palestinians want Obama to prove there are consequences if his call for an Israeli settlement freeze is again ignored -- as it is currently ignored with construction of subdivisions.

And their grievances are evident in more personal ways: Posters on Ramallah streets sarcastically advise Obama not to bring his smartphone because Israel does not allow 3G or better service in the Palestinian territories.

Poll: Most Americans say Israel is a friend

According to a new CNN/ORC International poll, 46% of Americans surveyed said Israel is an ally of the U.S., and 33% said the country's not an ally but friendly. Only 8% say Israel is unfriendly, with 6% calling the country an enemy of the U.S.

But if Israel were to attack Iran to prevent Iran from developing nuclear weapons, Americans were split on how the United States should react.

Of those polled, 49% said the U.S. should support Israel, while another 49% said the country should not get involved.

CNN's John King, Paul Steinhauser and Ashley Killough contributed to this report.